Space WI: Apollo program utilises Earth orbit rendezvous for lunar landings

Okay, cool. So based on the posts so far, how things are turning out:

1. Saturn C-4 (named "Saturn IV") as the main launch vehicle. 99 tonnes to LEO versus 140 tonnes. Astronautix has the C-4 cost per launch as $58 million, versus $494 million for Saturn V. Can't possibly be correct, surely? I also wonder about the logistics of launching two Saturn IVs so close together - three days if in 185 km orbit, or 30 days in a 270 km orbit, according to Michel Van. Fastest ever turnaround of Saturn V launches was about 60 days.

2. Delay of 6-8 months and an extra cost of $1 billion if NASA goes with EOR? That's according to this. So the first moon landing might takes place in late 1969.

3. Smaller CSM than OTL. Allows for easier conversion to Earth orbit operations (space stations). OTL Block II had endurance of 14 days; Apollo 17 pushed it to the limit with 12 twelve days. Presumably, it's still built with fuel cells providing power, with a solar power version waiting for later.

4. Enlarged LM. Performs LOI. Longer surface stays and the possibility of bring all three men down to the surface. Limits of CSM mean a stay of no more than seven days. Could be modified over its lifetime for greater capability - so it with start out with two-crew and building up to longer stays. Problem is how do you test it - Saturn IB is too small to launch a unmanned version like Apollo 5. Do you do the first test with a manned crew, or do you launch it on a Saturn IV, and waste two-thirds of the payload? Or -- and this might be stretching the finances and engineering too far -- do you use a Saturn IV flight to launch the test LM and a test space station module?

5. So! How I imagine things working prior to the first lunar landing:

July 1966 -- AS-203 (one Saturn IB): tested restart capability of S-IVB. Accident resulted in S-IVB being destroyed about six hours into the flight. Second test approved to ensure S-IVB could restarted after three days (OTL, the S-IVB was approved for use on the Saturn V after just AS-203, despite the premature destruction of the S-IVB).

August 1966 -- AS-204 (one Saturn IB): second test of restart capability of S-IVB. Successful refired after three-day loiter period for arrival of Apollo CSM/LM stack.

October 1966 -- AS-202 (one Saturn IB): second unmanned test of Block I Apollo.

January 1967 -- Apollo 1 fire? Probably happens anyway. Failure of AS-203 and the second test flight needed pushes it back to March/April 1967. If it doesn't happen then we can assume fatal consequences down the line.:(

November 1967 -- Apollo 4 (one Saturn IV): first test of Saturn IV launch vehicle/Block II CSM heat shield. Problems with the S-IVB don't push it back, problems with S-II does, built by North American Aviation, the same company that built the fault Block I CSM. So it probably flies first around the same time as OTL Apollo 4 did.

January/February 1968 -- Apollo 5 (one Saturn IV): second test of Saturn IV launch vehicle/Block II CSM heat shield. Also a test of how long it takes to prepare for another Saturn IV flight after a previous one. LM test delayed prior to determining no problems Saturn IV. Potential third test cancelled as unnecessary.

May 1968 -- Apollo 6 (one Saturn IV): first unmanned, orbital test of LM. Extra payload capacity opens up interesting possibilities of what could be launched with the LM.

October 1968 -- Apollo 7 (one Saturn IB): first manned, orbital test of Apollo CSM.

December 1968 -- Apollo 8 (two Saturn IBs): Tested rendezvous and docking with Apollo CSM and S-IVB; modified docking mechanism launched with manned Saturn IB to enable CSM to dock with S-IVB without LM, due to delays with Grumman. S-IVB test-firing takes crew to elliptical high Earth orbit. (OTL lunar orbit mission doesn't happen, because the docking needs to be tested.)

Late 1968/Early 1969 -- Manned Soviet Zond flight around the Moon?

March 1969 -- Apollo 9 (one Saturn IB, one Saturn IV): First American spacecraft to deliver manned crew to lunar orbit. Used Saturn IB to launch CSM and Saturn IV to launch S-IVB. Judged necessary to test fully-fueled S-IVB launched on Saturn IV. CSM docked with same mechanism used on Apollo 8, and once checks were all completed, proceeded to moon. Flight also politically important to demonstrate US superiority (Soviets might be the first to fly by the moon, but America was the first to orbit it).

May 1969 -- Apollo 10 (one Saturn IB, one Saturn IV): Manned test of LM in Earth orbit. Completed CSM/LM stack docked with S-IVB for test firing in addition to other LM tests.

July 1969 -- Apollo 11 (two Saturn IVs): "Dress rehearsal" for first manned landing. First launch of two Saturn IVs so close together; CSM/LM docks with S-IVB after just two days. First test of LM in lunar orbit.

November 1969 -- Apollo 12 (two Saturn IVs): First manned lunar landing. Pete Conrad and Alan Bean touch down in Sea of Tranquility on November 20, 1969.

(Of course this timeline is up for debate. I wonder if another test/modified test is needed to have two Saturn IVs launch to orbit before attempting to do it with a lunar orbit flight.)

(Another thought: with so many extra Saturn IBs being launch there might be an incentive to develop an alternate launch vehicle for that size payload (20,000 kg). MOL was cancelled around this time, how quickly could Titan IIIM be converted to launch an Apollo CSM? If they stick to the planned MOL timetable it might be ready to fly for the first Skylab missions (assuming it's exactly the same station.;)).)
 
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Okay, cool. So based on the posts so far, how things are turning out:

1. Saturn C-4 (named "Saturn IV") as the main launch vehicle. 99 tonnes to LEO versus 140 tonnes. Astronautix has the C-4 cost per launch as $58 million, versus $494 million for Saturn V. Can't possibly be correct, surely? I also wonder about the logistics of launching two Saturn IVs so close together - three days if in 185 km orbit, or 30 days in a 270 km orbit, according to Michel Van. Fastest ever turnaround of Saturn V launches was about 60 days.

I'd believe that a per-launch cost of about 70-80% of the Saturn V would be more reasonable. Less metal, smaller LV, and most likely a higher flight rate which trims the per-launch costs.


3. Smaller CSM than OTL. Allows for easier conversion to Earth orbit operations (space stations). OTL Block II had endurance of 14 days; Apollo 17 pushed it to the limit with 12 twelve days. Presumably, it's still built with fuel cells providing power, with a solar power version waiting for later.

14 days for a crew of 3 IIRC, and OTL, it was tested to 11 days for a three-man crew with Apollo 7, but Hydrogen Boil-off for the Fuel Cells would be the main limiting factor here. Batteries for a short(ish) duration LEO mission is another possible candidate.


4. Enlarged LM. Performs LOI. Longer surface stays and the possibility of bring all three men down to the surface. Limits of CSM mean a stay of no more than seven days. Could be modified over its lifetime for greater capability - so it with start out with two-crew and building up to longer stays. Problem is how do you test it - Saturn IB is too small to launch a unmanned version like Apollo 5. Do you do the first test with a manned crew, or do you launch it on a Saturn IV, and waste two-thirds of the payload? Or -- and this might be stretching the finances and engineering too far -- do you use a Saturn IV flight to launch the test LM and a test space station module?

Adding a station on top of the LEM is pushing it, OTL, the Saturn V was used for the LEO test of the CSM/LM together so wasting that payload is more than likely.


5. So! How I imagine things working prior to the first lunar landing:

*Snip*

March 1969 -- Apollo 9 (one Saturn IB, one Saturn IV): First American spacecraft to deliver manned crew to lunar orbit. Used Saturn IB to launch CSM and Saturn IV to launch S-IVB. Judged necessary to test fully-fueled S-IVB launched on Saturn IV. CSM docked with same mechanism used on Apollo 8, and once checks were all completed, proceeded to moon. Flight also politically important to demonstrate US superiority (Soviets might be the first to fly by the moon, but America was the first to orbit it).

*Snip*

November 1969 -- Apollo 12 (two Saturn IVs): First manned lunar landing. Pete Conrad and Alan Bean touch down in Sea of Tranquility on November 20, 1969.

Could happen. But a Centaur with the means to get the smaller CSM into LLO and use the CSM itself for TEI might also be an option. Only one Saturn IV needed for that.


(Another thought: with so many extra Saturn IBs being launch there might be an incentive to develop an alternate launch vehicle for that size payload (20,000 kg). MOL was cancelled around this time, how quickly could Titan IIIM be converted to launch an Apollo CSM? If they stick to the planned MOL timetable it might be ready to fly for the first Skylab missions (assuming it's exactly the same station.;)).)

OTL, the Titan III was tested with the 7-segment UA1207's for the cancelled MOL - and later employed on the Titan IV - so it's definitely an option they'd consider IMHO.

There's one other detail to be noted. How would this impact the Soviet Effort? Given that IOTL Korolev switched from his expensive but capable three-N1 EOR to single-N1 LOR due to funding constraints - only enough for 4 N1s per year - that made LOR the only viable option.
 
Irony on Titan IIIM, NASA wanted it as Titan IIIF, but as Unmanned rocket with various upper stages like Agena, Transtage, Centaur etc.
and yes there were proposal to Use Titan IIIM as Apollo CSM launcher,
But not inside NASA Administration, they look toward the Space Transportation System what became Space Shuttle

in end Titan IIIF was canceled al together with Titan IIIM and the Manned spy sat.
more ironic the Titan III had to fly to 1986/87 and Space Shuttle had to take over USAF Payload
but januar 1986 change that tragically
 

Archibald

Banned
the Saturn V was used for the LEO test of the CSM/LM together so wasting that payload is more than likely.

In fact nothing was really wasted in Apollo 9. The S-IVB was fully fueled and (I realized that only recently) after Apollo 9 µCSM/LM detached it was restarted and fired without any payload, into a solar orbit to simulate a TLI burn.
 
In fact nothing was really wasted in Apollo 9. The S-IVB was fully fueled and (I realized that only recently) after Apollo 9 CSM/LM detached it was restarted and fired without any payload, into a solar orbit to simulate a TLI burn.
Then perhaps TTL's Apollo 6 (LM alone on Sat4) might also make use of the S-IVB for a similar TLI simulation?

As far as rapid launch capability, the VAB was built such that multiple Saturn Vs could be prepared in parallel, and there were duplicates of everything needed for a parallel-launch campaign: four main cells in the VAB, two pads, two crawlers, multiple Mobile Servicing Towers and three Mobile Launch Platforms. If two Saturn 4s needed to be launched rapidly, they could be prepared for launch in parallel provided the site was staffed accordingly.
 
Thanks for the replies, everyone!:)

I'd believe that a per-launch cost of about 70-80% of the Saturn V would be more reasonable. Less metal, smaller LV, and most likely a higher flight rate which trims the per-launch costs.
So we are looking at a cost of around $350-$400 million per launch, which is still pretty steep. Saturn IB cost $55 million per launch.

So still a big incentive to go with a cheaper alternative (Shuttle). On the other hand, the cost is lower in the long run. At the least it might squeeze out another lunar landing before the program is cancelled (up to Apollo 19?).

14 days for a crew of 3 IIRC, and OTL, it was tested to 11 days for a three-man crew with Apollo 7, but Hydrogen Boil-off for the Fuel Cells would be the main limiting factor here. Batteries for a short(ish) duration LEO mission is another possible candidate.
So we are looking at a Block III developed at a later date for any lunar missions beyond about two-weeks long.


The way I was looking at it, Apollo 13 and 14 would continue with the two-man landing. Afterwards there is enough experience with lunar operations that the Block II LM is used, where the entire three-man crew lands on the surface. Without the Block III CSM, a maximum of seven days surface time.

Adding a station on top of the LEM is pushing it, OTL, the Saturn V was used for the LEO test of the CSM/LM together so wasting that payload is more than likely.
In fact nothing was really wasted in Apollo 9. The S-IVB was fully fueled and (I realized that only recently) after Apollo 9 µCSM/LM detached it was restarted and fired without any payload, into a solar orbit to simulate a TLI burn.
Then perhaps TTL's Apollo 6 (LM alone on Sat4) might also make use of the S-IVB for a similar TLI simulation?
Okay. So ITTL on Apollo 6 the S-IVB launched the unmanned LM for launch tests in Earth orbit, then the J-2 engine is fired again to simulate a TLI burn.

Could happen. But a Centaur with the means to get the smaller CSM into LLO and use the CSM itself for TEI might also be an option. Only one Saturn IV needed for that.
Sounds good. So instead Apollo 9 uses a single Saturn IV launch with a payload of a manned CSM and Centaur, which brakes the CSM into lunar orbit, which then uses the CSM for the TEI burn. And if something goes wrong, the crew returns on a free trajectory anyway, and the US can say they're capable of the same thing as the Soviets.

OTL, the Titan III was tested with the 7-segment UA1207's for the cancelled MOL - and later employed on the Titan IV - so it's definitely an option they'd consider IMHO.
Irony on Titan IIIM, NASA wanted it as Titan IIIF, but as Unmanned rocket with various upper stages like Agena, Transtage, Centaur etc.
and yes there were proposal to Use Titan IIIM as Apollo CSM launcher,
But not inside NASA Administration, they look toward the Space Transportation System what became Space Shuttle

in end Titan IIIF was canceled al together with Titan IIIM and the Manned spy sat.
more ironic the Titan III had to fly to 1986/87 and Space Shuttle had to take over USAF Payload
but januar 1986 change that tragically
Yup. One way to offset the cost of the Saturn IV. Titan IIIM had a projected payload of 17 tonnes to LEO, enough for the smaller CSM but not enough for an extra payload (like a Mission Module). You could soup that with a Centaur upper stage; otherwise you would have to launch a separate, Apollo-derived supply vehicle, on another Titan.

If NASA chooses the Titan IIIM than that opens up some possibilities for the robotic program in the 1970s. If the IIIM is picked, that's an extra 1,600 kg over the Titan IIIE, more if an upper stage is included. Could mean heavier Viking and Voyager probes...

There's one other detail to be noted. How would this impact the Soviet Effort? Given that IOTL Korolev switched from his expensive but capable three-N1 EOR to single-N1 LOR due to funding constraints - only enough for 4 N1s per year - that made LOR the only viable option.
If EOR is chosen by the Americans then that might make it more likely for Korolev to attain approval for his three-N1 plan.

Saturn C-5 was selected in December 1961 (ITTL the C-4 was selected instead), the decision was made public in January 1962. IOTL planning continued for a while with EOR assumed as the way the missions would be done, the decision to go for LOR was made in April 1962. So instead with a smaller payload on the C-4 EOR remains the preferred method for conducting the mission. The Soviet decision for a single N1 was only made in July 1964. So there is time for them to change their views.

If the Soviets try to copy the Americans (as they did with Buran) then instead of the N1-L3 they develop a lighter N1 with a plan for EOR.

But if Korolev switched to the N1-L3 because of budget restraints... well, maybe he can modify his plans to use two N1s instead.

As far as rapid launch capability, the VAB was built such that multiple Saturn Vs could be prepared in parallel, and there were duplicates of everything needed for a parallel-launch campaign: four main cells in the VAB, two pads, two crawlers, multiple Mobile Servicing Towers and three Mobile Launch Platforms. If two Saturn 4s needed to be launched rapidly, they could be prepared for launch in parallel provided the site was staffed accordingly.
Good to know.
 
Some more ideas:

- Uprated Saturn IV. Using the F-1A and J-2S engines with a number of UA1207 Titan-derived SRBs. Designed to eliminate need of two Saturn IV launches for each lunar landing, instead using a single Saturn IVA (?) for a lunar flight.

- Development of an intermediate launch vehicle between Saturn IB or the Titan IIIM (c. 20,000 kg) and the Saturn IV (c. 100,000 kg). A lot of proposals were made based on the Saturn V. Could be something like the Saturn INT-20 (which we might call the Saturn III): the three-engine variant could launch 35,000 kg, the four-engine version 60,000 kg. Would use elements common to the Saturn IV - the S-IVB stage and F-1 engines.

- American space stations. These alternate Saturns could launch more reasonably-sized station modules than Skylab. OTOH, desire or need to continue lunar flights could mean that a wet workshop design is chosen instead. Something like:

-- 1973-74: Skylab, wet workshop, launched on one of the last Saturn IBs, includes Apollo Telescope Mount
-- 1975-76: Skylab II, wet workshop, hosts ASTP, launched on new Saturn III. Docking module for Soyuz delivered by Apollo supply vehicle launched on Titan IIIM.
-- 1978: Freedom, first launch of custom main module on Saturn III Heavy (four F-1 engines instead of regular 3, up to 60 tonnes to LEO). Additional modules launched on Titan IIIM or Saturn III.

- Lunar missions. Budget cuts require the end of twice-yearly missions, so only one Apollo per year to the moon. Block III CSM allows crew stays of up to 14 days on the surface. Further development of the Saturn IV allows for the launch of a second, unmanned LM that acts as a habitat for the crew, boosting surface stays to up to 90 days.

- Soviet ambitions? We might actually see a Soviet lunar landing with a two-N1 architecture. N1 actually gets rated safe to fly in its lighter, 75 tonne variant. First lunar landing in 1970; maybe even a joint American-Soviet lunar expedition in the late 1970s?:eek:
 
Some more ideas:

- Uprated Saturn IV. Using the F-1A and J-2S engines with a number of UA1207 Titan-derived SRBs. Designed to eliminate need of two Saturn IV launches for each lunar landing, instead using a single Saturn IVA (?) for a lunar flight.

The Saturn IV, as I understand, had a higher T/M Ratio than the larger Saturn V in spite of just 80% of the Lift-Off Thrust due to the smaller 1st and 2nd stages, as such the use of F-1As (which have a sea-level thrust advantage of ~16.5% over their predecessors) along with SRBs will create aerodynamic stress issues that could well create some serious headaches.


- Development of an intermediate launch vehicle between Saturn IB or the Titan IIIM (c. 20,000 kg) and the Saturn IV (c. 100,000 kg). A lot of proposals were made based on the Saturn V. Could be something like the Saturn INT-20 (which we might call the Saturn III): the three-engine variant could launch 35,000 kg, the four-engine version 60,000 kg. Would use elements common to the Saturn IV - the S-IVB stage and F-1 engines.

The question here is, for what? It helps to have a payload to justify the Launch Vehicle.


- American space stations. These alternate Saturns could launch more reasonably-sized station modules than Skylab. OTOH, desire or need to continue lunar flights could mean that a wet workshop design is chosen instead. Something like:

-- 1973-74: Skylab, wet workshop, launched on one of the last Saturn IBs, includes Apollo Telescope Mount
-- 1975-76: Skylab II, wet workshop, hosts ASTP, launched on new Saturn III. Docking module for Soyuz delivered by Apollo supply vehicle launched on Titan IIIM.
-- 1978: Freedom, first launch of custom main module on Saturn III Heavy (four F-1 engines instead of regular 3, up to 60 tonnes to LEO). Additional modules launched on Titan IIIM or Saturn III.

This is perhaps one justification for a Saturn III LV, but IIRC, the Wet Workshop was demonstrated to be difficult to adapt for a crew in microgravity, and of lesser capability than the Dry Workshop.

Furthermore, the 99,000 Kg limit of the Saturn IV meets the requirement for OTLs 88,000 Kg Skylab, so I can't really see a serious reason why they wouldn't consider that.


- Lunar missions. Budget cuts require the end of twice-yearly missions, so only one Apollo per year to the moon. Block III CSM allows crew stays of up to 14 days on the surface. Further development of the Saturn IV allows for the launch of a second, unmanned LM that acts as a habitat for the crew, boosting surface stays to up to 90 days.

Depends on how much the budget is cut by, but since a small Lunar Hab is possible on a single Saturn IV, even if unmodified, it's not impossible.


- Soviet ambitions? We might actually see a Soviet lunar landing with a two-N1 architecture. N1 actually gets rated safe to fly in its lighter, 75 tonne variant. First lunar landing in 1970; maybe even a joint American-Soviet lunar expedition in the late 1970s?:eek:

This is likely. AFAIK, the reliability woes of the N1 IOTL came from trying to push the LEO payload from 75,000 Kg to 95,000 Kg, with all kinds of methods employed to lighten it, increase the engine performance, and slashing the error margins they had for it.

2 launches with this N1 is really their best bet.
 
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